How to Make It
Whisk together mayonnaise, eggs, and vanilla in a large bowl until smooth.
Combine flour and next 7 ingredients in a large bowl. Stir in apple, tossing to coat; stir into mayonnaise mixture. Spread into a lightly greased 13- x 9-inch baking pan. Sprinkle evenly with Crumb Topping.
Bake at 350° for 45 to 50 minutes or until wooden pick inserted in center comes out clean.